Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine

Peter Bachant and Martin Wosnik
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Peter Bachant: Center for Ocean Renewable Energy, University of New Hampshire, 24 Colovos Rd., Durham, NH 03824, USA
Martin Wosnik: Center for Ocean Renewable Energy, University of New Hampshire, 24 Colovos Rd., Durham, NH 03824, USA

Energies, 2016, vol. 9, issue 2, 1-18

Abstract: Experiments were performed with a large laboratory-scale high solidity cross-flow turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-flow turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R e D ? 10 6 or an approximate average Reynolds number based on the blade chord length R e c ? 2 × 10 5 . A simple model that calculates the peak torque coefficient from static foil data and cross-flow turbine kinematics was shown to be a reasonable predictor for Reynolds number dependence of an actual cross-flow turbine operating under dynamic conditions. Mean velocity and turbulence measurements in the near-wake showed subtle differences over the range of R e investigated. However, when transport terms for the streamwise momentum and mean kinetic energy were calculated, a similar R e threshold was revealed. These results imply that physical model studies of cross-flow turbines should achieve R e D ? 10 6 to properly approximate both the performance and wake dynamics of full-scale devices and arrays.

Keywords: Reynolds number; cross-flow turbine; turbine performance; marine hydrokinetic energy; wind energy; vertical-axis wind turbine (VAWT); scale model (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View complete reference list from CitEc
Citations: View citations in EconPapers (26)

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